Echocardiographic Assessment of the Alterations in Pulmonary Blood Flow Associated with Ketamine and Etomidate Administration in Children with Tetralogy of Fallot.

BACKGROUND: Despite widespread uses of ketamine, the clinical studies determining its effect on pulmonary blood flow in children with tetralogy of Fallot (TOF) are lacking. Furthermore, the quantification of pulmonary blood flow is not possible in these patients, because pulmonary artery catheter is contraindicated. Therefore, the purpose of this study was to evaluate the changes in pulmonary blood flow by intra-operative transesophageal echocardiography after ketamine or etomidate administration in children with TOF.

METHODS: Eleven children each in the two clinical variants of TOF (group A-moderate to severe cyanosis; group B-mild to minimal cyanosis) undergoing intracardiac repair were prospectively studied after endotracheal intubation. A single bolus dose of ketamine (2 mg/kg) and etomidate (0.3 mg/kg) was administered in a random order after 15 minute interval. Hemodynamic, arterial blood gas, and echocardiographic measurements were obtained at 7 consecutive times (T) points (baseline, 1, 2, 4, 6, 8, and 15 minutes after drug administration).

RESULTS: Ketamine produced a significant reduction in VTI-T (velocity time integrals total of left upper pulmonary vein), RVOT-PG (right ventricular outflow tract peak gradient), and MG (mean gradient) in group A while those in group B had a significant increase in VTI-T, RVOT-PG, and RVOT-MG at time (T1, T2, T4, and T6; P = 0.00). This divergent behavior, however, was not observed with etomidate.

CONCLUSION: Etomidate does not change pulmonary blood flow. However, ketamine produces divergent effects; it increases pulmonary blood flow in children with minimal cyanosis and decreases pulmonary blood flow in children with moderate to severe cyanosis.